Effect of high pressure homogenization on microstructure and rheological properties of hazelnut beverage cold-set gels induced glucono-δ-lactone

In this study, high pressure homogenized (HPH) hazelnut beverage samples were acidified with glucono-δ-lactone (GDL) and rheological, structural and gel strength properties of the cold-set gels were characterized. Hazelnut beverage at a concentration of 10 g 100 mL−1 was treated with HPH up to 150 MPa pressure and then mixed with GDL (2 g 100 mL−1). Gelation of hazelnut beverages was observed with small deformation oscillatory measurements during 150 min. Hazelnut beverages acidified with GDL displayed shear thinning behavior due to decreasing viscosity with increasing shear rate, however, HPH led to an increase in apparent viscosities of cold set hazelnut beverage gels. Cold set hazelnut beverages were characterized as weak gel-like macromolecular dispersions due to storage modulus (G′) was higher than loss modulus (G″). Angular frequency dependence of complex modulus (G*) was studied to measure the strength of the cross-linking protein network of suspension systems by calculating a constant order of relaxation function (α) and concentration-dependent stiffness parameter (Aα). This study revealed for the first time that hazelnut proteins can form good gel structures with acidification, and gel properties can be improved by HPH treatment.